Material Characterization of Cu-Fluorinated Silicate Glass and Cu-Organosilicate Glass Systems at Elevated Temperatures

The interaction between Cu and low- k (low dielectric constant) materials, fluorinated silicate glass (FSG), and organosilicate glass (OSG), have been investigated by examining the sheet resistance, surface morphology, phase formation, and compositional depth profiles before and after vacuum annealing at 400-800°C. It is found that the sheet resistance values of Cu on FSG and OSG decrease after annealing at 400-700°C and slightly increase after annealing at 800°C. The decrease of sheet resistance occurs in conjunction with the growth of Cu grains of the as-deposited Cu films, while the increase of sheet resistance at 800°C is accompanied with the formation of holes on Cu films, which is more extensive on FSG than on OSG. X-ray diffraction did not show any new phases formed in both systems upon annealing. A slight Cu diffusion toward the dielectric layers after annealing at 700-800°C is observed for both systems. In addition, carbon atoms in the OSG layer diffuse into the Cu layer after annealing at 700-800°C. The interdiffusion and reaction characteristics of the two multilayer structures upon vacuum annealing are discussed. © 2002 The Electrochemical Society. All rights reserved.